In a soft recoil weapon system, a recoiling mass generally refers to the components that move in response to the firing energy and may encompass, for example, a breech or a ramming mechanism, recoil cylinders, recoil springs, and firing mechanism. The rearward impulse of firing the weapon, is partially cancelled by the forward momentum of the recoiling mass at the time of firing.
The recoiling mass is normally held out-of-battery by a latch mechanism against a series of compression springs. When the latch mechanism is released, the recoiling mass is accelerated forward by the compression springs. The pressure created by the ignition of the propellant gases will launch the projectile forward and will launch the recoiling mass rearward, against the force created by the compression springs.
When designing a soft-recoil system a balance is sought between the forward momentum of the recoil system and the firing impulse, to ensure that the round fires and the weapon relatches, while minimizing recoil forces. Since the weapon must perform under a variety of conditions, including variations in ambient temperatures and propellant performance as well as weapon orientations (quadrant elevations) and platform cants (slopes), it becomes necessary to compensate for these variations, in order to ensure latching and to minimize recoil loads.
Conventionally, hydro-pneumatic recoil systems are utilized on large-caliber weapons to accomplish this task, while some small caliber systems utilize ring springs.
The need to maintain relatively low recoiling loads so that the weapons can be mounted onto light mobile platforms, is further complicated by other factors. These factors include for example, ignition delays, the ability to react to abnormally high impulses, the ability to perform at greater temperature extremes, and the ability to perform at greater weapon cant.
Ignition delays may, in extreme cases, defeat the advantages of soft recoil. For instance, by the time the mortar cartridge ignites, the forward momentum of the recoiling mass is reduced to zero. In this case, the recoil forces increase significantly, making the weapon system less practical for light mobile platforms. Certain conventional weapons have addressed this problem by allowing a portion of the combustion gases to vent past the breech seal, thereby reducing the rearward momentum. However, this arrangement may reduce the muzzle velocity of the projectile.
Weapons must also be designed to withstand the largest expected chamber pressure for safe operation under the most extreme operating conditions. This pressure, known as the PMP (permissible individual maximum pressure) may be typically as high as 50% greater than ambient temperature firing pressures. Statistically, these conditions may arise 3 times per 10,000 rounds fired, but result in greatly increased recoil forces. The traditional method of addressing this concern is to either increase the recoil distance to keep the forces to an acceptable level, or to design larger, more durable components.
Additionally, mobile platforms must be able to engage a variety of targets under various environmental extremes, with increased quadrant elevation ranges, and be able to fire at a variety of platform orientations and cants. These factors tend to require reducing the forward momentum of the recoiling parts in order to guarantee latching, which in turn results in higher recoiling forces.
Conventional soft recoil weapon systems are faced with the problem of actively controlling the recoil velocity to compensate for atypical or extreme firing conditions, such as firing at temperature extremes, firing on severe cants, or when firing results in a late ignition. Variations in the conditions of the soft recoil systems can result in system malfunction or even failure.
The prominent issue with these conditions is that soft recoil systems are dependent upon timing and load balances. More specifically, situational firing conditions can cause the following recoil extremes:                1—The recoiling parts do not have sufficient velocity to re-latch after firing, requiring the user to re-cock the weapon.        2—The recoiling parts have excessive velocity, causing high recoil forces and/or weapon damage.        3—Venting propelling gases reduces muzzle velocity, which reduces flight distance and prevents the round from reaching its intended target, thereby potentially endangering friendly troops and/or civilians.        4—Retraction of the rammer to get firing pin to safe position is inherently dangerous.        5—Increased trunnion forces, as a result of delayed ignition or permissible individual maximum pressure (PMP) rounds, require increased weight of latches, pedestal, and cradle which leads to mobility and payload issues.        
The conventional methods for addressing the foregoing problems include for example:                1—Increasing the recoil stroke to keep firing loads within vehicle limits for permissible individual maximum pressure (PMP), late ignition, and vehicle cant conditions (increases overall weapon length and weight).        2—Reducing late ignition recoil loads by venting a portion of the propelling gases during firing (reduces muzzle velocity which results in a “short” round).        3—Increasing the size and load carrying capability of the latch mechanisms.        4—Limiting allowable firing conditions to a narrower ambient temperature and shallower cant angles.        
While the foregoing conventional methods provided a certain level of control to the soft recoil weapon systems, there still remains a need for a more efficient, active soft recoil control system that provides a bi-directional recoil containment, double strike prevention, and firing pin retraction.